Revert "gnu global: set path of default gtags.conf in wrapper"

This reverts commit bd0d64730a.

Setting GTAGSCONF is not an adequate solution as it prevents the use of
it and the way it was done also breaks gtags when it is called by
global.

Fixes NixOS/nixpkgs#26971

pkgs/development/tools/misc/global/default.nix

@@ -34,10 +34,8 @@ stdenv.mkDerivation rec {
     cp -v *.el "$out/share/emacs/site-lisp"
 
     wrapProgram $out/bin/gtags \
-      --prefix GTAGSCONF : "$out/share/gtags/gtags.conf" \
       --prefix PYTHONPATH : "$(toPythonPath ${pythonPackages.pygments})"
     wrapProgram $out/bin/global \
-      --prefix GTAGSCONF : "$out/share/gtags/gtags.conf" \
       --prefix PYTHONPATH : "$(toPythonPath ${pythonPackages.pygments})"
   '';